#include <iostream>
#include <string>
#include <cstdlib>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>

// Father -> read
// Child -> write

int main()
{
    // 1.创建管道
    int fds[2] = {0};
    int n = pipe(fds);
    if (n != 0)
    {
        std::cerr << "pipe error" << std::endl;
        return 1;
    }

    // 2.创建子进程
    pid_t id = fork();
    if (id < 0)
    {
        std::cerr << "fork error" << std::endl;
        return 2;
    }
    else if (id == 0)
    {
        // 子进程
        // 关闭不需要的fd 关闭read
        close(fds[0]);
        int cnt = 0;
        int total = 0;
        while (true)
        {
            std::string message = "h ";
            // message += std::to_string(getpid());
            // message += ", ";
            // message += std::to_string(cnt);

            //fds[1]
            total += ::write(fds[1],message.c_str(), message.size());
            std::cout << "total: " << total << std::endl;
            //cnt++;
        }
        sleep(2);

        exit(0);
    }
    else
    {
        // 父进程
        // 关闭不需要的fd 关闭write
        close(fds[1]);

        char buffer[1024];
        while(true)
        {
            ssize_t n = ::read(fds[0], buffer, 1024);
            
            if (n > 0)
            {
                buffer[n] = 0;
                std::cout << "child -> father, message: " << buffer<< std::endl;
            }    
            else if(n == 0)
            {
                //如果写端关闭
                //读端读完管道内的数据，读取时，就会读到返回值0
                //表示对端关闭，也表示读到文件结尾
                std::cout << "n: " << n << std::endl;
                std::cout << "child quit??? me too " << std::endl;
                sleep(1);
                break;
            }    
            close(fds[0]);
            break;
        }
        std::cout << std::endl;
        int status = 0;
        pid_t rid = waitpid(id, &status, 0);
        std::cout << "father wait child success: " << rid <<"exit code" << 
        ((status << 8)&0xFF) << " , exit sig"<< (status & 0x7F) << std::endl;
    }

    return 0;
}







